/* ============================================================
   nav.css — 顶部导航 + 汉堡菜单（导航组件专属样式）
   ============================================================ */

/* ========== NAV ========== */
.nav {
  position: fixed; top: 0; left: 0; right: 0; z-index: 1000;
  height: var(--nav-h);
  display: flex; align-items: center; justify-content: center;
  padding: 0 24px;
  transition: background 0.4s var(--ease), box-shadow 0.4s var(--ease);
}
.nav.scrolled {
  background: rgba(5, 13, 26, 0.92);
  backdrop-filter: blur(20px) saturate(1.4);
  box-shadow: 0 1px 0 rgba(12, 161, 184, 0.1);
}
.nav-inner {
  width: 100%; max-width: var(--max-w);
  display: flex; align-items: center; justify-content: space-between;
}
.nav-logo {
  display: flex; align-items: center; gap: 12px;
}
.nav-logo-icon {
  width: 36px; height: 36px;
  position: relative;
}
.nav-logo-icon svg { width: 100%; height: 100%; }
.nav-logo-img {
  height: 28px;
  width: auto;
  display: block;
}
.nav-logo-text {
  font-family: var(--font-cn);
  font-weight: 700; font-size: 18px;
  color: var(--white);
  letter-spacing: 2px;
}
.nav-logo-sub {
  font-family: var(--font-en);
  font-weight: 300; font-size: 11px;
  color: var(--lake-light);
  letter-spacing: 3px;
  text-transform: uppercase;
  margin-top: -2px;
}
.nav-links {
  display: flex; gap: 36px; align-items: center;
}
.nav-links a.active {
  color: var(--white);
}
.nav-links a.active::after { width: 100%; }
.nav-links a {
  font-size: 14px; font-weight: 400;
  color: rgba(255,255,255,0.7);
  transition: color 0.3s;
  position: relative;
  letter-spacing: 0.5px;
}
.nav-links a::after {
  content: '';
  position: absolute; bottom: -4px; left: 0; width: 0; height: 1.5px;
  background: var(--lake);
  transition: width 0.3s var(--ease);
}
.nav-links a:hover { color: var(--white); }
.nav-links a:hover::after { width: 100%; }
.nav-contact-btn {
  padding: 8px 24px;
  border: 1px solid var(--lake);
  border-radius: 4px;
  color: var(--lake-light) !important;
  font-size: 13px !important;
  letter-spacing: 1px;
  transition: all 0.3s !important;
}
.nav-contact-btn:hover {
  background: var(--lake) !important;
  color: var(--white) !important;
}
.nav-contact-btn::after { display: none !important; }
.nav-lang {
  display: flex; align-items: center; gap: 4px;
  font-family: var(--font-en);
  font-size: 12px; font-weight: 500;
  color: rgba(255,255,255,0.5);
  cursor: pointer;
  padding: 6px 0;
  letter-spacing: 1px;
  transition: color 0.3s;
}
.nav-lang:hover { color: var(--lake-light); }
.nav-lang .active { color: var(--white); }
.nav-lang .divider { color: rgba(255,255,255,0.2); margin: 0 2px; }

/* Hamburger */
.hamburger {
  display: none; flex-direction: column; gap: 5px; cursor: pointer;
  background: none; border: none; padding: 4px;
}
.hamburger span {
  display: block; width: 24px; height: 2px;
  background: var(--white);
  transition: all 0.3s var(--ease);
  transform-origin: center;
}
.hamburger.active span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.hamburger.active span:nth-child(2) { opacity: 0; }
.hamburger.active span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* Mobile menu */
.mobile-menu {
  display: none; position: fixed; top: var(--nav-h); left: 0; right: 0; bottom: 0;
  background: rgba(5, 13, 26, 0.97);
  backdrop-filter: blur(30px);
  flex-direction: column; align-items: center; justify-content: center; gap: 32px;
  z-index: 999;
}
.mobile-menu.open { display: flex; }
.mobile-menu a {
  font-size: 20px; color: rgba(255,255,255,0.8);
  transition: color 0.3s;
}
.mobile-menu a:hover { color: var(--lake-light); }

/* ========== RESPONSIVE (nav) ========== */
@media (max-width: 768px) {
  .nav-links { display: none; }
  .hamburger { display: flex; }
}